A Tale of Four Cities: How Smart Growth Can Shape the Future of the Washington, D.C. / Baltimore Region

Sorry Ben, there are now three things certain in life: death, taxes, and bumper-to-bumper traffic on I-95 from Washington, D.C. to Baltimore. Though these three things are certain today, they may not be tomorrow. While I’d love to discuss when science will allow humans to upload their consciousness to the cloud, and download themselves into a new body (aka “sleeve”), a new study has prompted me to think about the future of regional traffic as not just dependent on autonomous vehicles or better mass transit.

Researchers at the University of Maryland National Center for Smart Growth analyzed what the Washington, D.C / Baltimore region may look like from now until 2040. The “Engaging the Future” report contrasts four possible futures against a baseline scenario in which the region adds nearly 1 million additional commuters. Under the baseline “do-nothing” scenario, commute times could quadruple despite large increases in rail ridership.

Congestion in the region, already bad, is forecast to get significantly worse. In spite of large increases in rail ridership, vehicle miles traveled and hours traveled are set to increase, which will worsen traffic – especially on highways. Source: National Center for Smart Growth

So, what can be done? The researchers played with different inputs in their model, which can all be found on page 3. For the sake of simplicity, I’ll focus on three: (1) self-driving vehicles, (2) better public transit, and (3) fuel price. Assuming growth or decline in these three factors produced the following four future scenarios for the region.

Revenge of the Nerds: Cheap fuel and autonomous vehicles incentivize driving and sprawl

This is a future of rapid economic growth driven by low fuel prices, widespread adoption of self-driving vehicles, and a retreat from government regulation in the face of such economic success. When combined, these factors increase the capacity of existing expressways, reduce the cost of driving, and make travel time more productive as commuters can watch Netflix as their car drives them to work. If most people are in self-driving cars, congestion could be reduced as cars are able to travel closer together and cause fewer crashes, allowing existing highways to accommodate more vehicles. As a result, ridership on transit plummets, emissions from transportation rise, and more farmland and forests are converted into housing.

The widespread use of autonomous vehicles increases highway capacity by 50 percent, which dramatically reduces congestion. But as residents decentralize due to new housing patterns, vehicle miles and emissions increase. Source: National Center for Smart Growth

Free for All: Self-driving cars fail to take hold, low fuel prices exacerbate sprawl as more jobs and people move into the region

This scenario assumes little government regulation and a slow but steadily growing economy led by job and population growth throughout the region. Low fuel prices mean no major investments in mass transit, but public-private partnerships are forecast to invest in new tolled highways and the construction of an additional bridge to the Eastern Shore of Maryland. In this scenario, employment and housing disperses from urban areas, and households fill the formerly protected agricultural preserves of the inner suburbs, especially in Montgomery, Prince George’s, and Baltimore Counties. Though sprawl worsens, and mass transit ridership declines, congestion and transit time improve as jobs move to the suburbs, closer to commuters.

This scenario assumes a relaxation in development restrictions, which allows new residential developments to locate in the formerly rural areas of Montgomery, Baltimore, Prince George’s and Howard Counties. Source: National Center for Smart Growth

This scenario assumes low levels of self-driving cars, but strong economic growth as advancements in clean technology overpower the economic drag of rising fossil fuel prices. High-tech clusters expand throughout the region, and investments in transit and renewable energy greatly decrease emissions, improve travel times, and lower regional congestion. Local governments accommodate growth by increasing residential capacity in inner suburbs, especially around the expanding transit network. The changes in travel behavior are forecast to be dramatic in this scenario. Though vehicle miles traveled increases, congestion is reduced as more public transit accommodates new straphangers. As a result, transportation-related emissions are greatly reduced as vehicles become electrified and personal transit shifts to public transit.

In this scenario, transit ridership increases 21 percent over the baseline; about half due to the expanded network and half due to high fuel prices. Unlike the baseline, many more transit trips originate in the cores and inner suburbs, with a substantial increase in reverse commutes to transit-accessible inner suburb locations. Source: National Center for Smart Growth

Last Call at the Oasis: As gas prices quadruple and economic growth slows, governments respond with more investment in core transit and electric vehicle infrastructure

The last scenario envisions a future defined by scarcity. Declining world oil reserves quadruples gas prices and accelerates the transition to electric vehicles, but not self-driving cars. The changing structure of the economy directs growth to the city cores of the region, and both households and jobs concentrate near transit stations in urban centers or inner suburbs. A quadrupling of gas prices would cause dramatic changes in travel behavior. Transit ridership would increase significantly, and electric vehicle sales would rise, helping slash emissions from transportation. In addition, considerably less forest and farm land would be developed in this scenario, since the jobs and housing would be concentrated more toward transit hubs in city centers or inner suburbs.

When vehicle operating costs quadruple, travel behavior, and ultimately land use, change in expected ways. Households cluster in the inner suburbs, close to employment and services, and near existing and new rail transit stations. Source: National Center for Smart Growth

Travel behavior is profoundly affected by a fourfold increase in fuel costs, the lack of autonomous vehicles, and the concentration of households in suburban corridors. As a result, congestion could fall dramatically in this scenario, along with auto-related pollution.Source: National Center for Smart Growth

How policy can help shape the Washington, DC / Baltimore region

This modeling effort demonstrates that the Washington, DC / Baltimore region could grow in vastly different ways. If we are to maximize the potential of self-driving cars and electric vehicles to reduce congestion and transportation-related emissions, smart policy will be needed to help drive the adoption of these technologies even if gas prices remain low.

Policies that offset the cost of electric vehicles incentivize the installation of public charging infrastructure, and push the generation of renewable energy are a good start – and already on the books across the country. Additional regulations to ensure autonomous vehicles are powered by renewable electricity and, to the greatest extent possible, operate as shared rides, will also likely be important as self-driving technology encourages people to take a car over public transit.

Policy will also be needed to keep housing and jobs from expanding too far into agricultural preserves and forests beyond the inner ring of suburbs. Placing affordable housing near transit hubs will likely remain key to keep people using public transit, even if congestion is somewhat lessened from a widespread adoption of self-driving cars.

Lastly, it’s important to recognize that neither self-driving cars nor electric vehicles are a panacea to transportation-related emissions and congestion. Even if we have cleaner vehicles, if there are more people in the region buying more vehicles and driving them more, then a decrease in emissions from fuel efficient or electric vehicles could be at least partially offset by the sheer volume of new drivers in the region. That’s why housing and regional planning policy must be taken into account when looking at the holistic future of this region – and hopefully this report informs regional planners and other policymakers as they look to expand the productivity and environmental stewardship of the region.

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